Mg基LPSO相単結晶におけるキンク帯形成の転位-結晶塑性シミュレーション

Abstract

In this study, two-dimensional FE simulations for a single crystal of a Mg-based LPSO phase are performed to computationally reproduce a deformation kink in the LPSO phase using a dislocation-based crystal plasticity model for HCP crystals developed in our previous work. We take account of activities of only basal slip systems of which CRSSes are set to be consistent with the experimental results on the LPSO phase. In addition, the characteristic shape of the LPSO crystal caused by preferential growth along the a-axis is introduced into the specimen. Since we need to consider some initial imperfection to numerically express a buckling phenomenon such as the deformation kink, we assume a small inclination of the basal plane for the loading direction as the initial crystal orientation. Moreover, we apply rmin method for the slip increment to the analysis for stability of calculation. As a result of this simulation, we predict the kink band formation computationally through the accumulation of GN dislocation, disclination and the crystal lattice rotation. The validity of the present model is discussed by comparing obtained results with a well-known explanation for kink formation based on dislocation behaviors qualitatively. Then we conclude that the kink band is rapidly formed by localized basal slips.